Abstract

A new type of topographic acoustic surfacewaveguide which uses substrate anisotropy is described. In this guide the velocity reduction at the center of a hump or depression on the substrate is primarily due to the change in crystal cut rather than a reduction in material constraint as in other topographic guides. Experimental results obtained on the (001) apex of a 110 axis Bi12GeO20 rod are in good agreement with the predictions of a ``lenslike media'' theory based on parabolically approximated wavesurfaces.